My U.S. Pat. No. 5,217,681, issued Jun. 8, 1993, discloses a prestressed pressure vessel safety enclosure used as a pressure safety enclosure for a nuclear reactor pressure vessel or other primary system vessel containing fluid or gaseous material under high pressure. The special pressure vessel enclosure comprises a first pressure vessel containment assembly surrounding the primary pressure vessel. A pair of first upper and lower pressure vessel jackets are adapted to enclose and be spaced apart, respectively, from the upper and lower portions of the first pressure vessel containment assembly with the rims of the jackets adapted to be slidable and sealed with respect to the first pressure vessel containment assembly. The spaces between the jackets and pressure vessel containment assembly are filled with a high boiling point, low melting point metal. Upper and lower ring girders, connected to each other by tension tendon members, in conjunction with upper and lower jacket bearing plates and skirts are used to apply a force to the respective upper and lower jackets for moving the jackets toward or away from each other. This application of force achieves continuously adjustable compression in the pressure vessel safety enclosure walls in order to compensate for creep and relaxation of tendon members and of the enclosure walls.
As will be seen below, the present invention differs in a number of important respects from the invention of U.S. Pat. No. 5,217,681. Among other things, the present apparatus employs bellows in the construction thereof which operate as fluid barriers, confine lead material filler, and allow for relative movement of structural components of the apparatus in a controlled manner. Additionally, the apparatus disclosed herein incorporates connector tendons of a specialized construction, incorporating two sets of tendons, one of which is prestressed almost to yield point, and the other of which is prestressed to a lesser extent for the purpose to be described below.
The apparatus disclosed herein is a nuclear reactor vessel and incorporates a core catcher for the purpose of receiving and safely containing core material from a reactor melt-down. Applicant is aware of a publication entitled Containments for Future PWR--Reactors authored by J. Eibl, F. H. Schluter, H. Cuppers, H. H. Hennies, and G. Kessler, published August, 1991 in SMiRT 11 Transactions Vol. A which relates to a pressure-resistant core catcher system for the purposes of mitigating or avoiding the consequences of a melt-down of a nuclear core. Such design involves the construction of heavy concrete walls around and beneath the reactor vessel with ceramic pans and particle beds positioned on the base mat. Cooling water from the reactor sump is circulated inside the core catcher and after the accident, there is permanent access and/or communication between the core catcher, the failed pressure vessel, and the containment building. The reactor vessel is a conventional single-wall vessel. This arrangement also differs from the present invention in that the prior art core catcher is not an integral part of the reactor vessel.
The following United States patents are also believed to be representative of the state of the prior art: U.S. Pat. Nos. 3,433,382, issued Mar. 18, 1969, 3,775,251, issued Nov. 27, 1973, 4,192,718, issued Mar. 11, 1980, 3,445,971, issued May 27, 1969, U.S. Pat. No. 3,512,675, issued May 19, 1970, 3,653,434, issued Apr. 4, 1972, 3,606,715, issued Sep. 21, 1971, 5,229,067, issued Jul. 20, 1993, 5,047,201, issued Sep. 10, 1991, 4,859,402, issued Aug. 22, 1989, 4,650,642, issued Mar. 17, 1987, and 4,032,397, issued Jun. 28, 1977. Applicant has authored a paper entitled Prestressed Safety Enclosure (PSE) with Metallic Cushion for New or Existing Reactor Pressure Vessels, published in SMiRT 11 Transactions Vol. SD2 (August, 1991). The above-identified prior art does not disclose the features noted above believed to be novel with respect to the present invention.